Isset

If exist php

if (isset($var)) {
  // Code here
}

Php see if undefined

if (isset($variable)) { /* do something */ };

Isset js

if (typeof obj.foo !== 'undefined') {
}

Js isset

if (typeof obj.foo !== 'undefined') {
  // your code here
}

Source: stackoverflow.com

Isset

<?php
if (isset($_POST['name'])) $name = $_POST['name'];
else $name = '(enter your name)';
echo <<<_END
<html>
    <head>
        <title>Test</title>
    </head>
    <body>
    Your name is $name<br />
    <form method = 'post' action = 'count.php'>
        What's your name?
        <input type='text' name='name' />
        <input type='submit' />
    </form>
    </body>
</html>
_END
?>

Source: stackoverflow.com

Isset

<?php

$a = "3.1416";

if (isset($a)) // la variable $a está definida

unset($a); //ahora ya no está definida

?>

-1

Source: educacionadistancia.juntadeandalucia.es

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